splitter container

hi all,

in my program i'm using splitter container with 1 column and 4 rows. in first row there is a toolbar , in 2nd a simple tree, in 3rd again a toolbar and in 4th a simple tree. the problem is that when i move the 2nd toolbar a space between toolbar and tree appears. i want that whenever i move the toolbar the last row containing simple tree should adjust accordingly.

for this which method i can use.

thanks.